It's those A-Channel Lost, Hall Effect Errors, Excess Follower Errors, or Over Speed Errors that just make you crazy. Right? "Why me?" says you. Well, it's not you. It's most likely the signal transmission medium in the servo system. The encoder cable is the single most important, exposed component, in a servo's motion control system. Generally, it is sitting out there for the world to see, and gets stepped on, spilled upon, continuously bent, and thoroughly mistreated. Yet, the high frequency signals that course through it's many conductors are vitally important to the servo motion system's "Closed Loop" digital position and velocity information ("feedback"). With even one small conductor slightly damaged, the system is likely to generate a feedback error.
So, you've got an encoder error of some kind. Then, "Clean up your act!"
Try cleaning the pins and sockets on the cable and the connector of the motor. Spray a bit of contact cleaner onto and into the pins and sockets respectively, then, gently blow them dry with clean compressed air (wear safety glasses). Now, reconnect the cable, and try the system again. If you are fortunate, the servo control will be a "happy camper" again.
No Go on the clean scheme? Get out your Volt/Ohm/Multimeter...set it to stun...
If the cleaning idea is a bust, the problem may be an obvious or hidden break in the wires. Check the encoder cable for obvious damage such as cuts or crushing evidence. If all looks kosher, then the next step is to actually verify the conductivity of each conductor end to end, and the lack of conductivity of each conductor to the cable's shielding, back-shell and adjacent conductors*. You will need a pin-out drawing of your cable to fully ascertain the integrity of the conductors and terminations. (*Some cables have jumpers soldered between pins or sockets inside the military type connectors.) All servo manufacturers do things differently when it comes to Servo Amplifier to Motor connection. Hopefully, you have access to the specific component schematics, or pin-outs. If not, the World Wide Web is great resource. Start typing your search query.
In some cases, despite the seemingly passing grade of the cable after testing, it could still be the source of system errors. Only a known-good replacement cable can verify that. If, after testing and or replacement, the error/s are still hanging around, you will be staring the servo motor directly in the face. It, the servo motor, can cause those feedback errors too. More specifically, it would be the motor's integral encoder that could be the problem child.
That, is for the next entry...
